Jacob's sermon addresses the theme that the ancient covenants of the Lord with the people of Israel have not, and will not be, forgotten. The covenants are all to be fulfilled, whether Israel remembers them or not; whether scattered Israel remembers they are descendants of Israel or not. God's end of the covenant is remembered and will all be fulfilled. He uses other words from Isaiah to make the same point:
Hearken unto me, ye that follow after righteousness. Look unto the rock from whence ye are hewn, and to the hole of the pit from whence ye are digged. Look unto Abraham, your father, and unto Sarah, she that bare you; for I called him alone, and blessed him. For the Lord shall comfort Zion, he will comfort all her waste places; and he will make her wilderness like Eden, and her desert like the garden of the Lord. Joy and gladness shall be found therein, thanksgiving and the voice of melody. Hearken unto me, my people; and give ear unto me, O my nation; for a law shall proceed from me, and I will make my judgment to rest for a light for the people. My righteousness is near; my salvation is gone forth, and mine arm shall judge the people. The isles shall wait upon me, and on mine arm shall they trust. (2 Nephi 8: 1-5.)
We are reminded to think about the "rock" from which we came. As descendants from Abraham (even though we may have lost all memory of that descent), we are heirs of the covenant. Almost all of Israel has been scattered. When these prophecies are read in the last days and their fulfillment is imminent, most of those who are covered by the promises will not initially identify themselves with Israel. By conversion to the covenant itself, however, the covenant returns even if we cannot link ourselves through genealogy. Everyone who accepts the fullness of the Gospel becomes "adopted" into the covenant, and is a part of Israel. The Gospel promises to every convert they are heirs.
As certain as God's promises to Abraham are, so is His commitment to Israel. We read with wonder and faith about Abraham's audiences with God. He was the "friend of God." We have faith in these accounts of Abraham. Therefore, we ought also to have faith in the ultimate fulfillment of the promises made to him. Those promises will involve a great latter-day work. God promised it, Abraham's children are to be blessed by it, Nephi saw it, and Isaiah wrote words which can be used to describe it. We ought to realize God is engaged in a great work in the last days, and we are living in the time when it is unfolding.